Thank you for contacting eXtension. Where is this, geographically? The submission form states only "Outside United States", so it will be helpful to have a more specific location before I forward your question to an expert.
I live in South Yorkshire in the United Kingdom. The patch is about 25cm long and has a liquid efforvessing from the centre.
It doesn't appear to me as a biotic (fungal) issue, rather some fluid (hydrocarbon) that can be assessed by an analytical lab.